The objective of this study was to determine whether container size or incorporation of water-holding hydrogels in the container medium would affect growth of prairie perennials transplanted on a steep slope. Seedlings of pale-purple coneflower (Echinacea pallida Nutt.), rough blazingstar (Liatris aspera Michx.), gray-headed coneflower [Ratibida pinnata (Venten.) Barnh.], and little bluestem grass [Schizachyrium scoparium (Michx.) Nash.], were grown in 3.7-cm (1.46-inch) diameter tubes that were either 13 cm (5.1 inches) or 18 cm (7.1 inches) long containing either standard greenhouse mix or the mix amended with hydrogels Terra-sorb AG or Liqua-Gel, or a nonhydrogel experimental compound, GLK-8924. The seedlings were transplanted to the slope in May 1994, and harvested in June 1995. After two growing seasons, plants of pale-purple cone-flower and gray-headed coneflower from the longer containers were larger (dry weight) than those from the shorter containers. The blazingstar and little bluestem were unafffected by container size. Terra-sorb AG and Liqua-Gel did not significantly affect height growth of the prairie perennials. GLK-8924-amended medium resulted in smaller or similar height plants.